In a loudspeaker unit, the sound will usually be divided into two or more frequency bands, a lower and an upper frequency band. The lower band may be the so-called lower frequency range which may for example be from approximately 20 to 2 kHz, and a high frequency band which may for example be from 2 kHz to 20 kHz. In order to relay the sound in the lower frequency band, a transducer unit having a large membrane diameter such as for example a cone membrane is used. In the higher frequency band, a small diameter transducer unit is used, often a so-called dome membrane type transducer.
A particular problem by relaying sound and splitting it up in two or more characteristic frequency bands is the reproduction of the sound where the frequency bands are split,—i.e. in the example mentioned above around 2 kHz. Obviously, where the frequency band has been split into more than two distinct frequency bands, the problem is pre-sent with each split.
The split is usually done in order to reproduce the sound as true to the original sound as possible. The lower frequencies require a relatively large membrane in order to reproduce the sound which is as true to the original as possible. High frequency reproduction requires a relatively small membrane in order to reproduce the sound as truthfully as possible. Therefore, there is a conflict between reproducing lower frequencies and higher frequencies which in the art has been solved by providing transducer units having membranes of different sizes in order to accommodate and provide the sound as close to the original sound as possible. In the frequency area where the split is made, a compromise is reached for example by delimiting at 2 kHz, so that the lower frequencies closer to 2 kHz frequency will have a certain distortion as well as for the higher frequency band, the lower frequencies around the 2 kHz frequency will also have a distortion.
Another factor which also makes it desirable to split up the sound in order to receive a truthful sound reproduction, is the fact that the low frequency unit has a relatively narrow divergence in the midrange frequencies (short wave length in relation to the diameter of the membrane of the transducer unit) whereas the high frequency unit traditionally has a large divergence in the midrange area, and a narrowed divergence in the high frequency area. All in all, these factors lead to a very uneven frequency response characteristic of the sound. The present invention is especially concerned with providing a frequency response characteristic for the high frequency dome transducer which is superior to anything previously suggested in the art.